Extreme winds in the alpine causing natural avalanches.
Snow conditions vary from rock hard wind blown snow to deep powder. As always make sure your whole party is riding with a beacon, shovel & probe and is familiar with their equipment.
Above 2,500ft High
1,800 to 2,500ft Moderate
Below 1,800ft Moderate
Degrees of Avalanche Danger ?
Elevation: Above 2000′
Aspect: Lee of ridges, gullies, ridgetops
Terrain: Upper elevation terrain exposed to wind
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Fair
Elevation: Above 2500′
Aspect: All ?
Terrain: 35+ degrees steepness
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Decreasing
Forecaster Confidence: Poor
AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor
LIST OF AVALANCHE PROBLEMS <here>
SNOWPACK DISCUSSION: 12″ (30cm) of low density snow has fallen in the alpine in the last two days, and unexpected winds Tuesday picked up, then again Wednesday morning contributing to significant transport. Windslabs continue to build, and new ones are building in areas they haven’t been observed in previous days.
The Feb. 26 and Feb. 27 storms totaled 12″ (30cm) on the pass. The Feb. 22 storm brought 4″ to Valdez and 6″ to the pass and interior. Primarily north winds transported this new snow, creating new and adding to existing windslabs lee of ridges and gullies. The snowpack depth in any given area can vary widely now, with deep windslab formation over the last several weeks.
The combined effect of steady winds and sparse snow events is producing notable density and depth differences in the upper snowpack. The cold, clear weather of the past month between the 1/15 and 2/13 storms created a weak layer over the old snow and a poor bond for storm snow to adhere to. Moderate winds continue to transport snow in the upper elevations.
Persistent slabs are tricky to predict and generally carry higher consequences. Our persistent slab concern still exists and our test pits indicate the primary layer of concern is buried 2-6′ (60-180cm) beneath the surface. These layers are stubborn to trigger, but due to depth, will carry higher consequences. We’re still tracking the distribution above 2500′ and our recent snowpit tests are indicating this concern may no longer be widespread. Persistent layers will be easier to trigger near rocky outcrops and where snowpack is thinner.
Loose snow avalanches are possible at all elevations. This becomes an increased concern when you’re traveling in terrain where the consequences of being swept off your feet are higher.
Recent Avalanche Activity
Feb. 28 At least one naturally triggered avalanche which closed highway access. Prior to that, a few D1 avalanches observed recently – ranging in location from near the port on a north aspect, to the interior. See observations page for details. No additional signs of avalanches observed or reported near the pass.
|WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:|
|Temperature Forecast (Min/Max *F):||-8 / 0|
|Ridgetop Wind Forecast (direction/mph):||NE/19-100+|
|WIND & TEMPERATURE
PAST 24 hours
|Ferry Terminal||Thompson Pass|
|Average Wind Speed (mph) / Direction||20 / NE||70 / NE|
|Max Wind Gust (mph) / Direction||49 / NE||102 / NE|
|Temperature Min / Max (*F)||19 / 28||4 / 13|
Wednesday mostly sunny skies through Friday, then cloudy. Extreme north winds diminishing tomorrow.
Additional Info & Media
|SNOW HISTORY:||Valdez 2/27 AM||Thompson Pass 2/27 AM|
|24 Hour Snow / Water Equiv.||0”/ 0″||0″ / 0″|
|Storm Snow /Water Equiv. (2/27)||6” / 0.25″||4″ / 0.2″|
|Current Snow Depth||44″||84″|
|February Snow / Water Equiv.||24.9″ / 2.25″||31″ / 2.7″|
|Total Winter Snowfall / Water Equiv.||112.95″ / 24.38”||317″ / 33″|
|Snowload in Valdez||49 lbs/sq. ft.|
|SNOWFALL at OTHER STATIONS:
LAST 24 HRS / STORM TOTAL (Feb. 12) / STORM WATER EQUIV.:
|Nicks Valley at 4200 ft (in):||” / ” / “|
|Upper Tsaina at 1750 ft (in):||” / ” / “|
|Sugarloaf at 550 ft (in):||” / ” / “|
|SNOW DEPTH & WATER SURVEY (2/5/2018)||Depth||Snow Water Equivalent|
|Milepost 2.5 Valdez||22″||7.6″|
|Milepost 29 Worthington Flats||62″||19.4″|
|Milepost 37 Tsaina River bridge||52.6″||16.4″|
|This survey is done the first week of each month.|
- Northeast Prince William Sound NWS Weather Forecast
- Middleton Island Radar for Valdez area
- GOES Alaska water vapor satellite loop
- NOAA NWS Recreational spot forecast for Thompson Pass
- Thompson Pass MP 25.7 RWIS weather station 2740′ (Mesowest)
- Valdez Marine Ferry Terminal weather station sea level
- Nicks Happy Valley above MP 30 weather station 4200′ (scroll to Nicks Valley)
- Upper Tsaina River Snotel near MP 32 1750′
- Sugarloaf Snotel 551′
- Above Valdez Glacier Cryosphere program weather station 6600′ <map here>
- Valdez Blueberry Weather Plot observations (scroll to bottom: Valdez City)
- More Mountain Weather resources for Alaska
- GFS 16 Day Model for Valdez
- Model Average Meteogram for Valdez
SNOW CLIMATE ZONES:
- Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
- Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
- Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Photo of Thompson Pass
Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)
NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.
Free smart phone avalanche forecasts at: http://www.